Dalys

DR MUHAMMAD TAUSEEF JAVED

Disability Adjusted Life Years (DALYs) and the Traffic-Related Burden of Disease in California


MBBS.DPH.FCPS(CM)M.Phil(CM).Dip-Card


Quick Outline

• Background – Summary measures of health– Disability Adjusted Life Years (DALYs)– DALYs & the Global Burden of Disease study– Relevance for the Traffic Safety Center

• Methodology• Results• Conclusions• Future Directions


Measures of Population Health:

Mortality and Morbidity Measures # deaths, death rate, # injured, # head

injuries, # severe injuries, rate of injuries, #

hospitalizations

Summary Measures Aggregate mortality and morbidity into a

single measure

# years healthy life lost (DALYs, QALYs)


Summary Measures of Population Health: Why use them?

• Compare the health of one population with another• Analyze the benefits of health interventions for use

in cost-effectiveness analysis• Identify and quantify overall health inequalities

within populations• Informing debates on health policy• Monitor changes in the health of a given population• Attribute burden from risk factors

[WHO – Summary Measures of Population Health, 2002]


Disability Adjusted Life Years (DALYs)

• Measures healthy time lost from specific diseases and injuries in a population

• Comparable and additive across diseases Ex: Broken scapula = .5 DALYs lost

Protein deficiency = 2 DALYs lost

• Based on relatively accessible incidence data (ICD codes)


DALY Calculation (the easiest way)

Years of lost life (YLLs)

Inputs• Life expectancy at age of

death• Age at death

Years lost to disability (YLDs)

Inputs• Duration of disease/injury• Disability weight of

disease/injury• % long-term cases

+


DALY Calculation: an example

1 family dies– 10 year old girl– 8 year old boy– 38 year old mother– 42 year old father

YLLs from deaths– 70 year life expectancy– 73 year life expectancy– 46 year life expectancy– 33 year life expectancy

222 YLLs

2 people injured– 45 y/o woman – SCI– 55 y/o man – fractured rib

YLDs from injuries- Duration (36 year LE) *

Disability Wt (.725) = 26 YLDs- Duration (.115 years) * Disability

Wt (.199) = 0.02 YLDs

A Two-Car Collision

26.02 YLDs+ = 248.02 YLDs


DALY Calculations: Adjustments• Designed to allow tailoring to local social values

and specific applications for the DALYs• Age-weighting – weights the life of a 21 year-old

(for instance) more heavily than other ages according to societal preferences.

• Discounting – commonly used in economic analyses, recommended for DALYs if using the outcome measure in such analyses

• Caused much contention • DALYs can be calculated without such

adjustments


DALYs and the Global Burden of Disease

• WHO/World Bank Global Burden of Disease study outlined methodology for DALYs

• First attempt at a comprehensive picture of global health• Ranked diseases according to the number of DALYs • Projected rankings to 2020

• Quick results– Ranked 9th in cause of total DALYs in the world

in 1990– Still ranked 9th in 2000 estimates – Predicted to be ranked 3rd in 2020


DALYs and the Traffic-Related Burden of Disease in California

• DALYs as a measure of traffic-related outcomes in California– Different than that captured by mortality or injury

alone?• Characterize the traffic-related burden of disease

in more detail for age, gender, and ethnicity– By occupant, pedestrian, bicyclist, etc.

• Construct a database of traffic-related DALYs for California for use in comparisons to global, regional, state, and city trends.


Methods: Case Definitions

• GBD case definition for injury: “One that leads immediately to death or that is non-fatal

but severe enough to warrant hospital treatment.”

• “Road Traffic Accidents” category based on the E-codes on hospital discharge– CDC and the GBD recommendations do not entirely

coincide

• Each injury type has a specified disability weight, duration, % long-term cases in the GBD


Methods: DALY Calculation Data Sources

MortalityCA Vital Statistics

EPIC database

+ Age- and sex- specific deaths listed by ethnicity and county

+/- ICD-10 coding for 1999 and later

Morbidity OSHPD hospital

discharge dataEPIC database

+ Age- & sex-specific injuries by ethnicity and county

+ Injury by E-code and nature of injury codes

+/- ICD-9 coding-- Need individual level

data-- Coverage?


Methods: DALY calculationsYLLs and YLDs

• Ethnicity, gender, age by External injury category (Motor vehicle Occupant, Pedestrian, Motorcyclist, or Bicyclist)

• Using highest world life expectancy and 3% discount rate

• YLL calculation• YLDs – calculated for each type of injury and

body part injured by age, gender, and ethnicityEx: Amputation of upper limb for 50-55 y/o Asian males = x YLDs


Methods: DALY calculationsComparison Measures

• Sum YLLs and YLDs for population = DALYs• Calculate the # of deaths and the # of injuries for

same categories from same data• Test rank-order for DALYs, deaths, injuries,

others?• Compare rates to global, regional, national, city

(San Francisco, Los Angeles) DALY rates.


Results?

• Not much yet.• Gender and age DALY calculations by injury

category is complete (as of yesterday)• YLLs by ethnicity are complete while YLDs

are still being calculated


Preliminary Results: Gender

• Consistency of the distribution of total traffic-related burden between genders ~70%

California DALYs – 71% male

Regional DALYs – 70% male

World DALYs – 70% male

California deaths – 69% male

California injuries – 62% male


Preliminary Results: Ethnicity

FemalesGBD YLL

ratesCDC YLL

rates

Death Rate per 100,000 Males

GBD YLL rates

CDC YLL rates

Death Rate per 100,000

White 144 119 6 White 328 274 15Native American281 182 6 Native American302 201 13Hispanic 168 146 5 Hispanic 482 392 14Black 143 123 8 Black 387 349 8Asian 117 95 5 Asian 231 212 9

TotalsGBD

YLL ratesCDC YLL

rates

Death Rate per 100,000

White 472 393 10Native American 583 383 10Hispanic 650 537 10Black 531 473 8Asian 348 307 7

YLLs


Conclusions thus far…

• The epi data necessary for YLD calculation is limited.– Primary diagnosis may not be the most severe

injury underestimation• Traffic-related DALYs are largely

composed of the YLL (deaths)• Future analyses will be more challenging

with HIPPA system in place


Future directions…

• By how much can the burden be reduced? How low can we feasibly get it?

• How much of the burden is attributable to lack of restraint-use? How much could we reduce the burden if we increase seatbelt use by 5%? Would we get more DALYs if we decrease alcohol-related burden by 5%?

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